It has been long recognized in large building structures that the cost of heating or cooling the structure significantly impacts the bottom line of the large business enterprise that occupy these structures. It is also known that for a small business entities such as a clinic, office or retail structure total energy costs related to lighting, heating or cooling breaks down this way: 40% is for heating and cooling, 40% for lighting and the balance for business related equipment. The U.S. Department of Energy estimates that a substantial portion of the heating, cooling and lighting cost is wasted as a result of the lack of an economical, effective system to control it.
In the design stage of large business structures elaborate lighting, heating and cooling control systems are built into the structures at the outset with an expectation that significant energy savings translated into dollars will be realized for the businesses occupying these structures. In the smaller business building market almost all heating and ventilation systems employ a single zone HVAC unit to supply conditioned, heated or cool air to more than one distinct zone or room. Each room or zone may have different comfort requirements due to occupancy differences, individual preferences, exterior load differences or the different zones may be on different levels, thereby creating different heating or cooling requirements. This type of system is referred to a single zone HVAC unit because it is normally controlled from one centrally located ON/OFF thermostat controller. In a building which may have more that one zone and whose zones have different heating, cooling requirements, it becomes difficult to choose a good representative location for the thermostat controller.
In the technical literature which embrace patented technologies there have been a number of note worthy attempts to provide systems that address the problems of controlling the different needs of more than one zone which is provided heating and cooling from a single zone HVAC.
One such U.S. patent is that of Tate et al U.S. Pat. No. 4,969,508 (508) in which the temperatures in the room(s) are controlled by means of a wireless portable remote control unit which may be hand held by the room occupant. The wireless remote control unit transmits information to a remote receiver in the ceiling of the room, which in turn provides signals to a main control unit physically coupled to external environmental control units such as the air conditioning system, heater, damper motors and the like.
The wireless remote control unit of the '508 patent in addition to being able to select heating and cooling modes may also operate in an energy saving mode. To this end a light sensing circuit is provided for overriding preselected conditions when the lights in the room are off. An infra red transmitter is employed for transmitting data to an infra red receiving unit on the ceiling when the lights are on.
The subject invention distinguishes over the '508 patent in that there is no requirement for individually motor powered dampers in the air supply ducts adjacent each zone to be controlled. Use of the subject invention allows for a simple installation of a self contained automatically controlled register. The '508 patent further requires wiring of the entire duct work system to provide power of the many power driven dampers employed. The subject invention avoids this by not requiring such wiring and therefore making it easier and less expensive to install.
Another approach to providing multiple heating/cooling zones which employ a single zone HVAC unit is shown and described in the Parker et al U.S. Pat. No. 4,530,395 ('395). The Parker et al arrangement provides zone control in plural zones in which each zone includes a control thermostat that is interfaced with a monitoring system so that each zone thermostat controls the HVAC unit as well as a damper unit for that particular zone. More specifically the system is comprised of two or more computerized thermostats which control both the HVAC unit through the monitoring control and the air distribution system of each zone through the damper for each zone. The thermostats also operate under control of signals received from the monitor.
The '395 is classic in its complex solution to the very simple concern of independently and automatically controlling the temperature in one of many zones simultaneously. The '395 patent like the '508 just reviewed requires electrically powered motors for each air flow control damper provided for each zone. The subject invention requires no such complex wiring and may be readily installed in air and existing HVAC system by simply removing a selected air distribution register and placing within an exposed air supply duct the apparatus of the instant invention. A wireless thermostat control device hung on a wall of a zone wall completes the installation of the subject invention in almost no time at all with little labor cost.
In yet another multiple zone system having a single central HVAC unit Robert S. Didier in his U.S. Pat. No. 4,479,604 ('604) shows and describes a controller for a central plant feeding a plurality of adjustable zone regulators which bring their respective zones to corresponding target temperatures. The controller has a plurality of temperature sensors and a plurality of zone actuators. The temperature sensors distributed one to a zone, each produce a zone signal signifying zone temperature. The zone actuators each have a zone control terminal. Each actuator can, in response to a signal at its zone control terminal, operate to adjust a corresponding one of the zone regulators. The controller also has a control means coupled to each of the temperature sensors and to the zone control terminal of each zone actuator for starting the central plant. The central plant is started in response to a predetermined function of zone temperature errors (with respect to their respective target temperatures) exceeding a given limit. The systems considers the temperature error in each of the zones. When the sum of the errors exceeds a given number, the furnace or air conditioner can be started.
In addition to the distinctions offered in respect of the '508 and '395 patents the subject invention is amazingly simple in design and generates its own power to thereby obviate the need of complex wiring system inherent in the '604 patent.